This invention relates to image-receiving elements and to diffusion transfer photographic products and processes utilizing same. More particularly, it relates to the utilization of an image-receiving element in a diffusion transfer product adapted to the provision of diffusion transfer images in the form of transparencies.
Diffusion transfer photographic products and processes have been described in numerous patents, including, for example, U.S. Pat. Nos. 2,983,606; 3,345,163; 3,362,819; 3,415,644; 3,573,044; 3,594,164; and 3,594,165. In general, diffusion transfer photographic products and processes involve film units having a photosensitive system including at least one silver halide layer, usually integrated with an image-providing material, e.g., an image-providing dye. After photoexposure, the photosensitive system is developed, generally by uniformly distributing an aqueous alkaline processing composition over the photoexposed element, to establish an imagewise distribution of a diffusible image-providing material. The image-providing material is selectively transferred, at least in part, by diffusion to an image-receiving layer or element positioned in a superposed relationship with the developed photosensitive element and comprising at least a dyeable stratum capable of receiving the imagewise distribution of image-providing material with formation of the desired transfer image.
Various formats have been utilized for the provision of color diffusion transfer images including the so-called "integral negative-positive" film units and so-called "peel-apart" formats. In accordance with the integral negative-positive film units, the image-receiving layer or element containing the photographic image for viewing can remain permanently attached and integral with the photosensitive or image-generating system or layers and the image is viewed through a transparent support against a suitable reflecting background. Such integral negative-positive formats are described, for example, in the aforementioned U.S. Pat. Nos. 3,415,644; 3,573,044; 3,594,164; and 3,594,165. Other, so-called "peel-apart", formats for color diffusion film units or assemblages are described, for example, in the aforementioned U.S. Pat. Nos. 2,983,606; 3,345,163; and 3,362,819, and involve the separation of the image-receiving element from the photosensitive element after development and transfer of the dyes to the image-receiving layer. The image is viewed, after separation of the elements, as a reflection print where an opaque support for the image-receiving layer is utilized or as a transparency image where a transparent support material is employed.
Image-receiving elements suited to the provision of reflection prints or transparencies, by separation from the photosensitive system after development and dye transfer, will typically comprise a suitable support, having thereon a neutralizing or acid-reacting layer for control of the environmental pH of the diffusion transfer process, a timing or spacer layer in conjunction with the neutralizing layer to control the initiation and rate of capture of alkali by the neutralizing or acid-reacting layer and a dye image-receiving layer. Such image-receiving elements and further details concerning their use in diffusion transfer film units or assemblages can be found in the aforementioned U.S. Pat. No. 3,362,819.
It has been known that the particular permeability characteristics of a polymeric layer utilized as an alkaline solution-permeable timing or spacer layer in a diffusion transfer product or process may greatly influence the quality of diffusion transfer photographic images. Thus, there is described in each of U.S. Pat. Nos. 3,419,389 (issued Dec. 31, 1966 to H. C. Haas et al.); 3,421,893 (issued Jan. 14, 1969 to L. D. Taylor); 3,443,633 (issued Mar. 18, 1969 to H. C. Haas); 3,455,686 (issued July 15, 1969 to L. C. Farney et al.); and 3,575,701 (issued Apr. 20, 1971 to L. D. Taylor), the advantageous utilization as polymeric timing or spacer layers of polymeric materials which exhibit permeability to the alkali of an alkaline processing composition inversely with increasing temperature. Such materials permit improved processing temperature latitude and obviate image defects which result from overextended maintenance of pH or premature pH reduction.
While polymeric layers which exhibit permeability to alkali according to an inverse temperature dependency advantageously provide improved processing temperature latitude, certain deficiencies in such polymeric layers may be observed. Thus, a polymeric timing layer exhibiting inverse-temperature permeability characteristics may be utilized in an image-receiving element adapted to the provision by diffusion transfer of a transparency image on a suitable transparent support. The conditions to which a transparency is subjected under normal conditions of usage determine in great measure the suitability of the various materials or components employed in the manufacture of such transparency. For example, defects such as reticulation in a timing or other layer may become apparent as the result of photographic processing with an aqueous alkaline processing composition. Thus, reticulation in a transparency, depending upon the degree of magnification employed for projection viewing, may become especially noticeable or objectionable.
In addition to consideration of physical defects in a transparency and their manifestations under conditions of usage, an image-receiving layer utilized in a transparency must be capable of mordanting or otherwise fixing a sufficient quantity of image-forming dye as to provide acceptable color saturation. Relative to an image-containing layer of a reflection print, the image-containing layer of a transparency, viewed by transmitted rather than reflected light, will have a greater density of image-forming dye. A suitable image-receiving layer for a transparency will, thus, have appreciable mordanting capacity so as to permit the attainment of adequate dye-image saturation.
It is an object of the present invention to provide an image-receiving element adapted to the provision of a transparency by photographic diffusion transfer processing over a range of temperatures.
It is another object of the present invention to provide such an image-receiving element suited to the provision of transparencies free of objectionable reticulation.
Still another object of the present invention is the provision of an image-receiving element adapted to the provision of transparencies exhibiting high dye-image density or saturation.
It is another object of the present invention to provide a diffusion transfer product and process effective for the provision of such transparency images.
Other objects will become apparent from the description appearing hereinafter.